JP2003123793A - Cation conductor and electrochemical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cation conductor prevented from decomposition over a wide temperature range (0-130 deg.C at least) including a room temperature in spite of presence of water, chemically stabilized for showing high proton conductivity over a long term, capable of taking a three-dimensional crosslinked structure for securing insolubility in water in spite of increase in the number of introduced acid functional groups, and reducing fluidity at a low temperature for improvement of heat resistance and to provide an electrochemical device such as a fuel cell using this cation conductor. SOLUTION: In this cation conductor, an organic residual group -Y- having an acidic group such as SO3 H and another substituent -Z such as OH are respectively connected to a fullerene molecule, or alternatively, the fullerene molecule is connected to the inside of polymer via the substituent or the organic residual group connected to the fullerene molecule (especially, the three-dimensional crosslinked structure is formed). In this electrochemical device such as the fuel, cell, the cation conductor is arranged between a hydrogen electrode 2 and an oxygen electrode 3 to serve as a proton conduction part 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cation conductor such as a proton conductor and an electrochemical device such as a fuel cell.

[0002]

2. Description of the Related Art In recent years, much attention has been paid to fuel cells from the viewpoint of environmental problems such as air pollution. In order to reduce air pollution as much as possible, measures against exhaust gas from automobiles have become important, and electric cars are used as one of the measures, but they have not come into widespread use due to problems such as charging equipment and mileage. On the other hand, an automobile using a fuel cell is expected to have the most potential, and it is necessary to study further higher efficiency and smaller size.

Fuel cells using a solid electrolyte as a power source for such automobile power sources and portable appliances have been actively researched. Known as such solid electrolytes are proton conductors such as polyperfluorosulfonic acid (such as Nafion manufactured by DuPont) and polymolybdic acid.

These polymer solid electrolytes are in a wet state.
When placed, it exhibits high proton conductivity near room temperature. Immediately
Take polyperfluorosulfonic acid as an example.
Protons ionized from the rufonic acid group are polymer matrix
Binds with a large amount of water (hydrogen bond)
Protonated water, that is, oxonium ion (H ₃
O⁺) Is produced and the form of this oxonium ion is taken.
The protons can move through the polymer matrix.
This type of matrix material can be
Shows the conduction effect.

However, this polymer solid electrolyte is
Since proton conduction is exhibited only in a humidified state, it is necessary to continuously keep it in a sufficiently humid state during use. Therefore, the configuration of the system such as the fuel cell requires a humidifying device and various associated devices, which inevitably increases the scale of the device and raises the cost of system construction.
In addition, there is a problem that the freezing of water occurs at low temperature, and the proton conductivity decreases due to evaporation of water at high temperature.

Further, in order to improve the efficiency and downsizing of the fuel cell, the proton conductor thin film must be made thinner in the polymer solid electrolyte type fuel cell, and the proton conductor itself has a high function. There is a growing demand for new products. In general, the polymer solid electrolyte as described above has a one-dimensional structure having a functional group that contributes to proton conduction, such as SO ₃ H group, at the tip of the side chain so that the main chain and side chain are fluorinated to have hydrophobicity. Although a polymer is used, such a one-dimensional polymer remarkably swells or solubilizes in water if the amount of the acid functional group introduced is increased excessively in order to improve conductivity.

[0007]

Accordingly, the present applicant has found that fullerenol and hydrogen sulfate esterified fullerenol exhibit proton conductivity, and the novel proton conductors are disclosed in Japanese Patent Application Nos. 11-204038 and 2000-058116. Was raised. The proton conductor according to the invention of the prior application can be used in a wide temperature range including normal temperature, its lower limit temperature is not particularly high, and water as a transfer medium is not required, and the proton conductor has a small atmosphere dependency. Is.

FIGS. 18 (A) and 18 (B) show fullerene molecules C ₆₀ and C ₇₀ , but in the invention of the prior application, carbon atoms constituting these fullerene molecules are changed to those shown in FIG. 19 (A). Polyhydroxylated fullerene (commonly known as "Fullereno (Fullereno)
l) ”or as shown in FIG. 19 (B), a proton conducting part is formed by polyhydroxylated fullerene hydrogensulfate, which is a compound in which the hydroxyl group of fullerenol is replaced with a sulfone group. Is a simplified representation of the fullerene molecule).

Such fullerenol or its hydrogen sulfate ester has an OH group or OSO _{3 in} one molecule of fullerene.
Since a large number of proton-dissociative groups consisting of H groups are introduced, they exhibit proton conductivity even in the absence of water, and the number density per volume of proton transfer sites as a proton conductor increases. In this case, proton conductivity is more remarkable in the polyhydroxylated fullerene hydrogensulfate ester of FIG. 19 (B) in which a sulfone group is introduced into the constituent carbon atoms of the fullerene molecule than in fullerenol.

[0010]

However, such polyhydroxylated fullerene hydrogensulfate, which is a fullerenol derivative, exhibits high proton conductivity even under non-humidified conditions, but under high temperature conditions (especially 85 ° C.). that's all)
It was found that the sulfate ester moiety was easily hydrolyzed. Therefore, in the presence of water (this is also the case with the water produced on the oxygen electrode side as a result of the battery reaction), when used at high temperature, there is a problem that the proton conductivity tends to decrease. did.

The object of the present invention is that even in the presence of water, it does not decompose in a wide temperature range including normal temperature (at least 0 ° C. to 130 ° C.), is chemically stable, and is stable for a long time. It is intended to provide a cation conductor having proton conductivity, and an electrochemical device such as a fuel cell using the cation conductor.

Another object of the present invention is that it is possible to have a three-dimensional cross-linking structure, does not solubilize in water even if the amount of acid functional groups introduced is increased, and the fluidity at high temperature is further increased. Another object of the present invention is to provide a cation conductor that is also expected to be improved in heat resistance and an electrochemical device such as a fuel cell using the same.

[0013]

That is, the present invention relates to a cation conductor in which an organic residue having an acidic group and another substituent are bonded to a fullerene molecule, respectively. , An electrochemical device arranged between the first pole and the second pole. Hereinafter, these are referred to as the first cation conductor and the electrochemical device of the present invention.

According to the first cation conductor and electrochemical device of the present invention, in the cation conductor, an organic residue having a proton-dissociative acidic group such as a sulfonic acid group is bonded to a fullerene molecule. Even under normal temperature and normal humidity (or non-humidified conditions), the acidic groups have many transport sites and exhibit high proton conductivity, and the organic residue that binds the acidic groups to the fullerene molecule undergoes decomposition such as hydrolysis. Since it is difficult to receive, the acidic group is retained by the fullerene molecule without decomposition even in the presence of water, and high proton conductivity can be retained for a long time.

Moreover, the presence of the above-mentioned substituent bonded to the fullerene molecule, particularly the active group capable of polymerization, causes the fullerene molecule to bond to the polymer through this substituent (in particular, to form a three-dimensional crosslinked structure). Is possible. Due to such polymerization, decomposition does not occur in a wide temperature range including at room temperature (at least 0 ° C to 130 ° C), fluidity at high temperature is suppressed, and it is chemically stable, and the introduction of the acidic group is performed. Even if the amount is increased, it becomes possible to form a three-dimensional crosslinked structure that is insoluble in water, and does not dissolve into water that exists or is generated during the operation of an electrochemical device such as a fuel cell. It shows stable high proton conductivity over time.

In the present invention, an organic residue having an acidic group and another substituent or organic residue are bonded to a fullerene molecule, respectively, and the fullerene molecule is bonded to the fullerene molecule via the substituent or organic residue. The present invention provides a cation conductor bound in a united body, and also provides an electrochemical device in which the cation conductor is arranged between a first pole and a second pole. Hereinafter, these are referred to as the second cation conductor and the electrochemical device of the present invention.

According to the second cation conductor and electrochemical device of the present invention, in the cation conductor, an organic residue having a proton-dissociative acidic group such as a sulfonic acid group is bonded to a fullerene molecule. Similarly to the first cation conductor and the electrochemical device of the present invention, even under normal temperature and normal humidity (or non-humidified) conditions, the acidic groups have many transport sites and exhibit high proton conductivity. Since the organic residue that binds the group to the fullerene molecule is less susceptible to decomposition such as hydrolysis, the acidic group is retained by the fullerene molecule without causing decomposition even in the presence of water,
High proton conductivity can be maintained for a long time.

Moreover, since the fullerene molecule is bonded to the polymer through the substituent or the organic residue bonded to the fullerene molecule (particularly forming a three-dimensional crosslinked structure), a wide temperature range including normal temperature Range (at least 0 ° C-130
Degradation does not occur at (° C), fluidity at high temperature is suppressed, it is chemically stable, and it has a three-dimensional crosslinked structure that is insoluble in water even when the amount of the acidic group introduced is increased. Therefore, it does not dissolve into water that exists or is generated during the operation of an electrochemical device such as a fuel cell, and thus exhibits stable and high proton conductivity for a long time.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION In the first and second cation conductors and electrochemical devices of the present invention, the organic residue preferably has 1 to 20 carbon atoms, and N, O, P, S
Etc. may be included in the hetero atom. Further, it is preferable that 2 to 14 of the organic residues are bonded to one molecule of fullerene and one or more of the substituents are bonded to one molecule of fullerene.

The acidic group is preferably a proton dissociative group such as a sulfonic acid group, a carboxyl group or a phosphoric acid group.

The substituents are C, N, O, P,
A functional group containing a hetero atom such as S, F, Cl, Br or I,
Alternatively, it may be a polymerizable active substituent having active hydrogen, such as a sulfonic acid group, a hydroxyl group, an amino group, a carboxyl group, a mercapto group, a phosphoric acid group.

It is preferable that the substituent is crosslinked with a crosslinking agent such as polyisocyanate, or the fullerene molecule is crosslinked with the organic residue.

The fullerene molecule is specifically a spherical carbon molecule C _m (m = 36, 60, 70, 76,
78, 80, 82, 84 and the like, which are natural numbers capable of forming spherical molecules.

Then, it is preferable that the proton conducting portion made of a cation conductor is constructed as a fuel cell arranged between the hydrogen electrode and the oxygen electrode.

Next, preferred embodiments of the present invention will be described with reference to the drawings.

As illustrated in FIG. 1, the cation conductor (fullerene derivative as a proton conductor) of the present invention represented by the general formula (I) has an organic residue (--Y-- or --R ^1).
-) through a sulfonic acid group, a carboxyl group, proton dissociating acidic substituent such as phosphoric acid groups, for example sulfonic acid groups (-SO ₃ H), but also active substituents (-Z), for example hydroxyl groups, It is a fullerene polyhydroxyalkyl sulfonic acid represented by the general formula (1), which is chemically bonded radially to a fullerene molecule C ₆₀ . This cation conductor exhibits high ionic conductivity in a wide temperature range including at room temperature (at least 0 ° C. to 130 ° C.) and is not hydrolyzed even in the presence of water and is chemically stable for the reasons described above. It is a conductive compound.

In the general formulas (I) and (1), p (the number of substituents) is p ≧ 1 and is not particularly limited, but is preferably 2 to 14, for example 2 to 6. When this p is small, the ionic conductivity tends to be low, and when p is large, the number q of Z or OH groups decreases and the crosslinkability becomes poor. Further, q (the number of substituents) is 1 or more, for example, 2
4, when the amount is small, the crosslinkability becomes poor, and when the amount is 4, p is decreased and the ionic conductivity is easily lowered. These compounds having too much p and q cause steric hindrance, and thus are difficult to synthesize.

Further, Y and R ¹ in the general formulas (I) and (1) represent all organic residues having 1 to 20 carbon atoms. This compound having 1 to 2 carbon atoms is difficult to dissolve in a solvent, and for example, the solubility of the solvent in ion exchange becomes poor,
Further, a compound having 5 or more carbon atoms tends to be difficult to synthesize, and the acidic group density decreases, so that the carbon number is 1 to 4,
Particularly, 3 or 4 is preferable. When the number of carbon atoms exceeds 20, the organic residue is bulky and the ionic conductivity of the acidic group is adversely affected.

Examples of Y and R ¹ are a chain or branched alkylene group (for example, methylene group, ethylene group, trimethylene group, tetramethylene group, ethylethylene group, propylene group), aromatic group (for example, Phenylene group and naphthylene group). This Y and R ¹
May contain a hetero atom such as N, O, P and S (for example, oxy group, carbonyl group, thio group, thiocarboxyl group, sulfinyl group, sulfone group, imino group, azo group, phosphone group). Etc.).

In addition, the active substituent Z in the general formulas (I) and (1) may be an unsubstituted form, and N, O, P, S,
It may be a functional group containing a hetero atom such as F, Cl, Br or I. Examples thereof include an alkyl group such as a methyl group and an ethyl group, a fluorine group, a chloro group, a methoxy group and a methylthio group.

Z is an active substituent (for example, an active functional group having active hydrogen such as a sulfonic acid group, a hydroxyl group, an amino group, a carboxyl group, a mercapto group and a phosphoric acid group). , And a cross-linking agent (polyisocyanate-based, dihalogen-based, diol-based, dithiol-based, epoxy-based, diazide-based, dicarboxylic acid-based, etc.) three-dimensionally cross-links into a polymer and can be made insoluble in water. .

The compound shown in FIG. 1 (fullerene polyhydro
For example, the reaction for synthesizing
As shown in 2, the number of alkyl sulfonic acid groups to be introduced
2 to 30 equivalents of reducing agent with respect to fullerene (eg,
For example, alkali metal naphthalenide) and sulfonating agent (eg
For example, alkyl sultone) is used. In this reaction, R ¹
SO introduced via₃Fullere with Na
NaOH, (R²)_FourTreatment with NOH and ion exchange
By conversion, -SO₃Na as a sulfonic acid group, and
Introduce an OH group into the olefin molecule. Good ionic conductivity
To achieve this, preferably 15 to 30 equivalents of reducing agent and
And a sulfonating agent are required. Of these, less than 10 equivalents
In case of, the number of introduced sulfonic acid groups (p) is small
And when p exceeds 15, the target compound is almost obtained.
No further excess of reactants is
Is unnecessary.

As the reducing agent, an alkali metal naphthalenide (an alkali metal is Li,
A reducing reagent such as Na or the like, the same applies hereinafter) or an alkali metal ditertiary biphenyl may be used, and in addition to this, an electrochemical method using a reducing action of electrons supplied from an electrode may be adopted.

The compound of the general formula (1) has a weight average of 15
% Of water molecules may be firmly incorporated as crystal water, and this crystal water is at a high temperature of about 100 ° C. and 10 ^−6.
It does not desorb even under the high vacuum of Torr. That is, since this compound forms a proton conduction channel composed of these water of crystallization and a sulfonic acid group as a bulk solid, it exhibits high ionic conductivity over a wide temperature range including normal temperature. This compound exhibits good ionic conductivity even in a dry environment, but under humid conditions, higher ionic conductivity can be realized due to the presence of water.

The compound represented by the general formula (II) in FIG.
As another cation conductor (proton conductor) of the present invention, a fullerene molecule is bound to a polymer. This compound has an organic residue (—Y— or —R ¹ —) bonded to the fullerene molecule that constitutes the monomer component of the polymer, like the compound of the above general formula (1). For the same reason as described above, an ion conductive compound which exhibits high ionic conductivity in a wide temperature range including at room temperature (at least 0 ° C. to 130 ° C.) and is not hydrolyzed even in the presence of water. Is. Incidentally, the organic residue in the compound (-Y- or -R ¹ -) is
Same as above.

In the compounds of the general formulas (II) and (2), the fullerene molecule as a polymer is bonded to the polymer chain through a substituent or an organic residue (R ³ ). Is an active substituent similar to Z in the above general formula (I), and is three-dimensional by a crosslinking agent (polyisocyanate type, dihalogen type, diol type, dithiol type, epoxy type, diazide type, dicarboxylic acid type, etc.). It is a cross-linked polymer and is insoluble in water. Shows a case of using a polyisocyanate (OCN-R ⁴ -NCO) in the general formula (2).

Alternatively, R ³ may directly crosslink the fullerene molecule and includes all organic residues having 2 to 20 carbon atoms and has an alkylene group (eg, methylene group, ethylene group, trimethylene group, tetramethylene group). Group), N,
Heteroatoms such as O, P and S may be included.
Examples thereof include an oxy group, a carbonyl group, a thio group, a thiocarboxyl group, a sulfinyl group, a sulfone group, an imino group, an azo group and a phosphone group.

Further, C, N, O,
It may have a substituent containing a hetero atom such as P and S. For example, methyl group, ethyl group, propyl group, butyl group, vinyl group, aryl group, methoxy group, ethoxy group, carboxyl group, methoxycarbonyl group, benzoyloxy group, formyl group, acetyl group, methoxymethyl group, methoxyethoxymethyl. Group, mercapto group, methylthio group, thioacetyl group, thiocarboxyl group, sulfino group, sulfonic acid group, mesyl group, amino group, methylamino group, anilino group, cyano group, nitro group, hydrazino group, phenylazo group, phosphate group And so on.

In the general formulas (II) and (2),
p and q are the same as above, but r (degree of polymerization)
Is preferably 3 or more.

A synthetic reaction of the compound shown in FIG. 3 (polymer of fullerene polyhydroxyalkyl sulfonic acid) is shown in FIG. 4, for example. The reaction up to the middle is performed in the same manner as in FIG. 2, but the obtained fullerene polyhydroxylalkyl sulfonic acid can be reacted with a polyisocyanate having the following structure to form a urethane polymer.

[0041]

Embedded image Polyisocyanate:

The above-described compounds of the present invention represented by the general formulas (I) and (II) both show high ionic conductivity as a proton conductor in a wide temperature range including normal temperature (at least 0 ° C. to 130 ° C.), It is also an ion conductive compound that is chemically stable. In particular, the compound of the general formula (II) has a fullerene molecule bonded in the polymer, and therefore has a crosslinked structure to improve water resistance and stably shows high proton conductivity for a long time.

FIG. 5A shows a specific example of a fuel cell using the above fullerene derivative (for example, fullerene polyhydroxyalkyl sulfonic acid or urethane polymer thereof) as a proton conductor. This fuel cell has a negative electrode (a fuel electrode or a hydrogen electrode) having terminals 8 and 9 facing each other, in which catalysts 2a and 3a are closely adhered or dispersed, respectively.
2 and a positive electrode (oxygen electrode) 3, and the proton conducting portion 1 is sandwiched between these two electrodes.

At the time of use, hydrogen is supplied from the inlet 12 on the negative electrode 2 side and discharged from the outlet 13 (this may not be provided). While the fuel (H ₂ ) 14 passes through the flow path 15, protons are generated, and as shown in FIG. 5 (B), the protons move to the positive electrode 3 side together with the protons generated in the proton conducting section 1, and there, It reacts with oxygen (or air) 19 which is supplied from the inlet 16 to the flow path 17 and goes to the exhaust port 18, whereby a desired electromotive force is taken out.

[0045]

EXAMPLES Examples of the present invention will be described below.

Example 1 <Synthesis of fullerene polypropyl sulfonic acid>

[0047]

[Chemical 2]

This synthesis is based on the literature (Y. Chi, JBBhonsle,
T.Canteenwala, J.-P.Hung, J.Shiea, B.-J.Chen and
LYChiang, Chem. Lett., 1998, 465.). To a solution of 2 g of fullerene powder in dimethoxyethane,
A solution of sodium naphthalenide in dimethoxyethane prepared in advance was added in an amount of 30 equivalents, and the mixture was stirred at room temperature under a nitrogen atmosphere for 2 hours. Then cool the reaction solvent in an ice bath,
After adding 30 equivalents of 1,3-propane sultone, 50 ° C
And stirred for 4 hours.

The reaction was stopped by adding methanol, and the precipitate was collected by filtration. The obtained precipitate was thoroughly washed with methanol.

The powder thus obtained was dissolved in pure water, passed through an ion exchange column for sulfonation, water was removed by an evaporator and then vacuum dried.

FT of the black powder thus obtained
When -IR (Fig. 6) and TOF-MS (Fig. 7) measurements were performed, it was confirmed to be fullerene polypropyl sulfonic acid (p in Fig. 7 represents the number of introduced propyl sulfonic acid groups. Represents).

Next, 80 mg of this fullerene polypropyl sulfonic acid powder was measured and pressed in one direction at a rate of about 5 tons / cm ² so as to form a circular pellet having a diameter of 15 mm.

A complex impedance plot was prepared using the pellets thus prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 60%, it was 20
1 × 10 ^-3 Scm ^-1 at ℃, 7 × 10 ^-3 Sc at 50 ℃
It was 1 × 10 ^-2 Scm ^-1 at m ^-1 and 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 1 at 85 ° C.
It was × 10 ^-2 Scm ^-1 .

<Synthesis of fullerene polyhydroxypropyl sulfonic acid>

[Chemical 3]

1 g of the above-mentioned precipitate (sodium fullerene polypropyl sulfonate) before ion exchange was added to 20 ml of an aqueous solution of sodium hydroxide (1 g / 1 ml) to dissolve it, and 3 drops of tetratert-butylammonium hydroxide was added thereto. The mixture was stirred for 2 hours, 30 ml of water was added, and the mixture was stirred for 12 hours. The reaction solution was concentrated with an evaporator, and methanol was added to precipitate a precipitate.
This was filtered, the solid component was further washed with methanol three times, and sodium hydroxide was completely removed using column chromatography (silica gel, water was used as a developing solvent).

The obtained powder was dissolved in pure water, passed through an ion exchange column, water was removed by an evaporator, and then 4
It was dried at 0 ° C. for 12 hours. When the FT-IR (FIG. 8) of the black powder thus obtained was measured, it was confirmed to be fullerene polyhydroxypropyl sulfonic acid.

Next, this fullerene polyhydroxy pro
Measure 80mg of Pyrsulfonic acid powder, diameter 15m
Approximately 5 tons / direction in one direction so as to form a circular pellet of m
cm ²Pressed at.

A complex impedance plot was prepared using the pellet thus prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 60%, it was 20
7 × 10 ^-3 Scm ^-1 at ℃, 8 × 10 ^-3 Sc at 50 ℃
It was 9 × 10 ⁻³ Scm ⁻¹ at m ⁻¹ and 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 9 ° C at 85 ° C.
It was × 10 ^-3 Scm ^-1 .

Example 2 <Synthesis of fullerene polybutyl sulfonic acid>

[0060]

[Chemical 4]

This synthesis is also carried out in the literature (Y. Chi, JBBhonsle,
T.Canteenwala, J.-P.Hung, J.Shiea, B.-J.Chen and
LYChiang, Chem. Lett., 1998, 465.). To a solution of 2 g of fullerene powder in dimethoxyethane,
20 equivalents of a previously prepared solution of sodium naphthalenide in dimethoxyethane was added, and the mixture was stirred at room temperature under a nitrogen atmosphere for 2 hours. The reaction solution was cooled in an ice bath, 30 equivalents of 1,4-butanesultone was added, and then the mixture was stirred at 50 ° C. for 4 hours.

The reaction was stopped by adding methanol, and the precipitate was collected by filtration. Further, the filtrate was concentrated, methanol was added to reprecipitate, and the precipitate was collected by filtration. The obtained precipitate was thoroughly washed with methanol.

The powder thus obtained was dissolved in pure water, passed through an ion exchange column, water was removed by an evaporator, and then vacuum dried.

FT of the black powder thus obtained
When -IR (Fig. 9) and TOF-MS (Fig. 10) measurements were performed, it was confirmed to be fullerene polybutyl sulfonic acid (p in Fig. 10 represents the number of introduced butyl sulfonic acid groups. Represents).

Next, 80 mg of this fullerene polybutyl sulfonic acid powder was measured and pressed in one direction at a rate of about 5 ton / cm ² so as to form a circular pellet having a diameter of 15 mm.

A complex impedance plot was prepared using the pellets thus prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 60%, it was 20
1 × 10 ^-3 Scm ^-1 at ℃, 7 × 10 ^-3 Sc at 50 ℃
It was 1 × 10 ^-2 Scm ^-1 at m ^-1 and 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 1 at 85 ° C.
It was × 10 ^-2 Scm ^-1 .

<Synthesis of fullerene polyhydroxybutyl sulfonic acid>

[0068]

[Chemical 5]

1 g of the above-mentioned precipitate (sodium fullerene polybutyl sulfonate) before ion exchange was added to 20 ml of an aqueous solution of sodium hydroxide (1 g / 1 ml) to dissolve it, and 3 drops of tetratert-butylammonium hydroxide was added thereto. The mixture was stirred for 2 hours, 30 ml of water was added, and the mixture was stirred for 12 hours. The reaction solution was concentrated with an evaporator, and methanol was added to precipitate a precipitate.
This was filtered, the solid component was further washed with methanol three times, and sodium hydroxide was completely removed using column chromatography (silica gel, water was used as a developing solvent).

The obtained powder was dissolved in pure water, passed through an ion exchange column, and water was removed by an evaporator, and then 4
It was dried at 0 ° C. for 12 hours. When the FT-IR (FIG. 11) measurement of the black powder thus obtained was performed, it was confirmed to be fullerene polyhydroxybutyl sulfonic acid.

Next, 80 mg of this fullerene polyhydroxybutyl sulfonic acid powder was measured and the diameter was 15 mm.
Approximately 5 tons / c in one direction to form a circular pellet
Pressed at m ² .

A complex impedance plot was prepared using the pellets thus prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 60%, it was 20
5 × 10 ^-3 Scm ^-1 at ℃, 7 × 10 ^-3 Sc at 50 ℃
It was 9 × 10 ⁻³ Scm ¹ at m ⁻¹ and 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 8 ° C at 85 ° C.
It was × 10 ^-3 Scm ^-1 .

In this example, the target product was obtained in the same manner as above except that the conditions for synthesizing the above fullerene polybutyl sulfonic acid were changed as shown in Table 1 below.

[0074]

[Table 1]

From these results, the TOF-MS spectra of the target substance obtained under the synthesis conditions are shown in FIGS. 12 to 16, respectively. When these results are considered together with the results of FIG. 10, sodium naphthalene The number of substituents increases as the equivalents of dode and 1,4-butane sultone increase, and the temperature is preferably higher than room temperature, but 50 ° C. is most suitable, and the reaction solvent is tetrahydrofuran, which is more polar than dimethoxyethane. Each proves to be suitable.

Example 3 <Synthesis of fullerene polyhydroxyoxybutyl sulfonic acid>

[0077]

[Chemical 6]

2 g of fullerenol (synthesis of fullerenol is described in Long Y. Chiang, Lee-Yih Wang, John W. Swirczewsk
i, Stuart Soled, and Steve Cameron, J.Org. Chem. 1
Conducted as per 994,59,3960. ) And 4.0 g of sodium hydride, 100 ml of dehydrated tetrahydrofuran as a solvent was added, and the mixture was stirred under nitrogen at 60 ° C. for 2 hours. Then, 1,4-butane sultone dissolved in 50 ml of tetrahydrofuran was added dropwise, and further under nitrogen at 60 ° C.
And reacted for 20 hours.

Methanol was added to terminate the reaction, and the precipitate was collected by filtration. The precipitate was thoroughly washed with methanol and hexane and vacuum dried for 12 hours.

The obtained powder was dissolved in pure water, passed through an ion exchange column, and the water was removed by an evaporator.
It was vacuum dried at 0 ° C. for 12 hours.

FT of the black powder thus obtained
When -IR (FIG. 17) measurement was performed, it was confirmed to be fullerene polyhydroxyoxybutyl sulfonic acid. According to elemental analysis, the introduced amount (p) of oxybutyl sulfonic acid group was 4 on average per 1 molecule of fullerene.

Next, 80 mg of this fullerene polyhydroxyoxybutyl sulfonic acid powder was weighed to obtain a diameter of 1
It was pressed in one direction at a rate of about 5 ton / cm ² into a circular pellet of 5 mm.

A complex impedance plot was prepared using the pellets thus prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 60%, it was 20
6 × 10 ^-4 Scm ^-1 at ℃, 4 × 10 ^-3 Sc at 50 ℃
It was 8 × 10 ⁻³ Scm ⁻¹ at m ⁻¹ and 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 8 ° C at 85 ° C.
It was × 10 ^-3 Scm ^-1 .

Example 4 <Urethane polymerization of fullerene polyhydroxybutyl sulfonic acid>

[0085]

[Chemical 7]

0.3 g of fullerene polyhydroxybutyl sulfonic acid powder was weighed and sufficiently dissolved in 0.4 g of pure water, and then polyisocyanate: aquanate 200
0.15 g (manufactured by Nippon Polyurethane Industry Co., Ltd.) was added and stirred with a centrifugal stirrer for 3 minutes to prepare a paste.

This paste was applied on a 20 μm thick polytetrafluoroethylene (trade name: Teflon: hereinafter the same manufactured by DuPont) sheet using a doctor blade with a 150 μm gap, and the sheet after application was placed in an environment of 80 ° C. After being dried for 48 hours, the coating film was peeled off from the Teflon sheet to obtain a urethane polymerized film of fullerene polyhydroxybutyl sulfonic acid. The film thickness is 26μ
It was m.

The obtained film was punched to have a diameter of 15 mm, a complex impedance plot was prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 60%, it was 5 × 10 ⁻⁴ Scm ⁻¹ at 20 ° C. and 2 × at 50 ° C.
It was 10 ⁻³ Scm ⁻¹ and 6 × 10 ⁻³ Scm ⁻¹ at 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 8
It was 6 × 10 ⁻³ Scm ⁻¹ at 5 ° C.

Example 5 <Urethane polymerization of fullerene polyhydroxyoxybutyl sulfonic acid>

[0090]

[Chemical 8]

0.3 g of powder of fullerene polyhydroxyoxybutyl sulfonic acid was weighed and sufficiently dissolved in 0.4 g of pure water, and then polyisocyanate: aquanate 2
0.15 g of 00 (manufactured by Nippon Polyurethane Industry Co., Ltd.) was added, and the mixture was stirred with a centrifugal stirrer for 3 minutes to prepare a paste.

This paste was applied onto a Teflon sheet having a thickness of 20 μm using a doctor blade having a gap of 150 μm, and the applied sheet was dried in an environment of 80 ° C. for 48 hours, and then the coating film was peeled off from the Teflon sheet. Thus, a urethane polymerized film of fullerene polyhydroxyoxybutyl sulfonic acid was obtained. The film thickness was 26 μm.

The obtained film was punched out to a diameter of 15 mm, a complex impedance plot was prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 60%, it was 5 × 10 ⁻⁴ Scm ⁻¹ at 20 ° C. and 3 × at 50 ° C.
It was 10 ⁻³ Scm ⁻¹ and 6 × 10 ⁻³ Scm ⁻¹ at 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 8
It was 7 × 10 ⁻³ Scm ⁻¹ at 5 ° C.

Example 6 <Polyurethane cross-linking of polyvinyl alcohol of fullerene polyhydroxybutyl sulfonic acid>

[0095]

[Chemical 9]

0.3 g of fullerene polyhydroxybutyl sulfonic acid powder was weighed and sufficiently dissolved in 0.4 g of pure water, and then polyvinyl alcohol (PVA) 0.05
g, polyisocyanate: Aquanate 200 (manufactured by Nippon Polyurethane Co., Ltd.) 0.10 g was added, and the mixture was stirred for 3 minutes with a centrifugal stirrer to prepare a paste.

This paste was applied onto a Teflon sheet having a thickness of 20 μm using a doctor blade having a gap of 150 μm, and the applied sheet was dried at 80 ° C. for 48 hours, and then the coating film was peeled off from the Teflon sheet. Then, a PVA urethane cross-linked film of fullerene polyhydroxybutyl sulfonic acid was obtained. The film thickness was 28 μm.

The obtained film was punched out to a diameter of 15 mm, a complex impedance plot was prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 60%, it was 4 × 10 ⁻⁴ Scm ⁻¹ at 20 ° C. and 1 × at 50 ° C.
It was 10 ⁻³ Scm ⁻¹ and 5 × 10 ⁻³ Scm ⁻¹ at 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 8
It was 5 × 10 ⁻³ Scm ⁻¹ at 5 ° C.

Example 7 <Urea cross-linking polymerization of fullerene polybutyl sulfonic acid polyamine>

[0100]

[Chemical 10]

0.3 g of fullerene polybutyl sulfonic acid polyamine powder was weighed and sufficiently dissolved in 0.4 g of pure water, and then polyisocyanate: aquanate 200
0.15 g (manufactured by Nippon Polyurethane Industry Co., Ltd.) was added and stirred with a centrifugal stirrer for 3 minutes to prepare a paste.

This paste was applied on a Teflon sheet having a thickness of 20 μm using a doctor blade having a gap of 150 μm, and the applied sheet was dried at 80 ° C. for 48 hours, and then the coating film was peeled off from the Teflon sheet. Thus, a urea cross-linked film of fullerene polybutyl sulfonate polyamine was obtained. The film thickness was 27 μm.

The obtained film was punched out to a diameter of 15 mm, a complex impedance plot was prepared, and the ionic conductivity was measured. When the same sample is measured in an atmosphere with a humidity of 60%, it is 5 × 10 ⁻⁴ Scm ⁻¹ at 20 ° C. and 1 × at 50 ° C.
It was 10 ⁻³ Scm ⁻¹ and 5 × 10 ⁻³ Scm ⁻¹ at 85 ° C. When the same sample was measured in an atmosphere of 100% humidity, it was 8
It was 5 × 10 ⁻³ Scm ⁻¹ at 5 ° C.

Example 8 <Synthesis of cross-coupling polymer of fullerene polybutyl sulfonic acid>

[0105]

[Chemical 11]

To 1 g of a solution of sodium fullerene polybutylsulfonate powder in dimethoxyethane was added 5 equivalent of a previously prepared solution of sodium naphthalenide in dimethoxyethane, and the mixture was stirred at room temperature under a nitrogen atmosphere for 2 hours. 4 equivalents of 1,12-dibromododecane were added, and the mixture was further stirred at room temperature under a nitrogen atmosphere for 12 hours.

The reaction was stopped by adding methanol, and the precipitate was collected by filtration. The precipitate thus obtained was treated with hydrochloric acid to obtain the target compound. The obtained compound was insoluble in water.

Next, 80 mg of the powder of the full-coupling polymer of fullerene polybutyl sulfonic acid was weighed and pressed in one direction at a rate of about 5 ton / cm ² so as to form a circular pellet having a diameter of 15 mm.

A complex impedance plot was prepared using the pellets thus prepared, and the ionic conductivity was measured. When the same sample was measured in an atmosphere with a humidity of 90%, it was 20
1.6 × 10 ^-4 Scm ^-1 at ℃, 7 × 10 ^-3 at 50 ℃
^{Scm -1, 7 × 10 -3 Scm} -1 at 85 ° C., was 1 × 10 ^-2 Scm ^-1 at 95 ° C..

[0110]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, in the cation conductor, a divalent organic residue having a proton-dissociable acidic group such as a sulfonic acid group is bonded to a fullerene molecule, so that it is kept at room temperature. Even under humid (or non-humidified) conditions, the acidic groups have many transport sites and exhibit high proton conductivity, and the organic residue that binds the acidic groups to fullerene molecules is less susceptible to decomposition such as hydrolysis. In addition, even if water is present, the acidic group is retained by the fullerene molecule without causing decomposition, and high proton conductivity can be retained for a long time.

Moreover, due to the presence of the above-mentioned substituent bonded to the fullerene molecule, the fullerene molecule can be bonded to the polymer through this substituent (or organic residue) (in particular, a three-dimensional crosslinked structure is formed). Since it becomes possible or is bonded, decomposition due to such polymerization does not occur in a wide temperature range including at room temperature (at least 0 ° C to 130 ° C), fluidity at high temperature is suppressed, and Is stable, and even if the amount of the acidic group introduced is increased, it becomes possible to form a three-dimensional crosslinked structure that is insoluble in water, and water existing or generated during the operation of an electrochemical device such as a fuel cell is generated. Therefore, it does not melt out, and thus shows stable high proton conductivity for a long time.

[Brief description of drawings]

1 is a schematic diagram showing the chemical structure of a fullerene derivative according to the present invention, for example, fullerene polyhydroxyalkyl sulfonic acid.

FIG. 2 is a schematic diagram showing a synthetic scheme of fullerene polyhydroxyalkylsulfonic acid.

FIG. 3 is a schematic diagram showing the chemical structure of a polymer of another fullerene derivative according to the present invention, for example, a urethane polymer of fullerene polyhydroxyalkyl sulfonic acid.

FIG. 4 is a schematic diagram showing a synthetic scheme of a urethane polymer of fullerene polyhydroxyalkyl sulfonic acid.

FIG. 5 is a schematic cross-sectional view (A) and an operation principle diagram (B) of a fuel cell according to one embodiment using, for example, fullerene polyhydroxyalkyl sulfonic acid or a polymer thereof according to the present invention as a proton conductor.

FIG. 6 is a spectrum diagram showing the FT-IR measurement results of fullerene polypropyl sulfonic acid obtained in the examples of the present invention.

FIG. 7: TO of fullerene polypropyl sulfonic acid
It is a spectrum figure which shows the measurement result of F-MS.

FIG. 8 is a spectrum diagram showing the measurement results of FT-IR of fullerene polyhydroxypropyl sulfonic acid.

FIG. 9 is a spectral diagram showing the FT-IR measurement results of fullerene polybutyl sulfonic acid obtained in another example of the present invention.

FIG. 10: TO of fullerene polybutyl sulfonic acid
It is a spectrum figure which shows the measurement result of F-MS.

FIG. 11 is a spectrum diagram showing the measurement results of FT-IR of fullerene polyhydroxybutyl sulfonic acid.

FIG. 12 is a spectrum diagram showing the result of TOF-MS measurement of another fullerene polybutyl sulfonic acid.

FIG. 13 is a spectrum diagram showing the result of TOF-MS measurement of another fullerene polybutyl sulfonic acid.

FIG. 14 is a spectrum diagram showing the TOF-MS measurement results of another fullerene polybutyl sulfonic acid.

FIG. 15 is a spectrum diagram showing a result of TOF-MS measurement of another fullerene polybutyl sulfonic acid.

FIG. 16 is a spectrum diagram showing measurement results of TOF-MS of still another fullerene polybutyl sulfonic acid.

FIG. 17: FT-IR of fullerene polyhydroxyoxybutyl sulfonic acid obtained in still another example of the present invention
It is a spectrum figure which shows the measurement result of.

FIG. 18 is a structural diagram of a fullerene molecule.

FIG. 19 is a schematic view of an example in which polyhydroxylated fullerene (A), which is an example of a fullerene derivative, and hydrogen sulfate (B) thereof are used as a proton conductor.

[Explanation of reference numerals] 1 ... Proton conducting part, 2 ... First electrode (hydrogen electrode), 2a ... Catalyst, 3 ... Second electrode (oxygen electrode), 3a ... Catalyst, 14 ... Hydrogen,
19 ... Oxygen (or air)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koji Inomata             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 4H006 AA01 AB46 AB84                 5G301 CD01                 5H026 AA02 AA06 CX05 EE17

Claims (20)

[Claims] 1. A cation conductor comprising an organic residue having an acidic group and another substituent bonded to a fullerene molecule. 2. An organic residue having an acidic group and another substituent or organic residue are bonded to a fullerene molecule, respectively, and the fullerene molecule is incorporated into the polymer via the substituent or organic residue. A cation conductor formed by bonding. 3. The cation conductor according to claim 1, wherein the organic residue has 1 to 20 carbon atoms. 4. The cation according to claim 1, wherein the organic residue has 2 to 14 bonds to one fullerene molecule, and the substituent has one or more bonds to one fullerene molecule. Conductor. 5. The cation conductor according to claim 1, wherein the acidic group is a proton dissociative group such as a sulfonic acid group, a carboxyl group or a phosphoric acid group. 6. The substituent is a functional group containing a hetero atom, or an active substituent having active hydrogen.
Or the cation conductor described in 2. 7. The cation conductor according to claim 2, wherein the substituent is crosslinked with a crosslinking agent. 8. The cation conductor according to claim 2, wherein the fullerene molecule is crosslinked by the organic residue. 9. The fullerene molecule is a spherical carbon molecule C _m.
(M = 36, 60, 70, 76, 78, 80, 82, 8
The cation conductor according to claim 1 or 2, which is composed of a natural number capable of forming a spherical molecule, such as 4. 10. The cation conductor according to claim 1, which functions as a proton conductor. 11. An electrochemical in which a cation conductor formed by binding an organic residue having an acidic group and another substituent to a fullerene molecule is arranged between a first pole and a second pole. device. 12. An organic residue having an acidic group and another substituent or organic residue are bonded to a fullerene molecule, respectively, and the fullerene molecule is incorporated into a polymer through the substituent or organic residue. An electrochemical device in which a cation conductor formed by bonding is arranged between a first pole and a second pole. 13. The electrochemical device according to claim 11, wherein the organic residue has 1 to 20 carbon atoms. 14. The electricity according to claim 11, wherein the organic residue has 2 to 14 bonds to one fullerene molecule, and the substituent has one or more bonds to one fullerene molecule. Chemical device. 15. The acidic group is a proton dissociative group such as a sulfonic acid group, a carboxyl group or a phosphoric acid group.
The electrochemical device according to claim 11 or 12. 16. The substituent is a functional group containing a hetero atom, or an active substituent having active hydrogen.
The electrochemical device described in 1 or 12. 17. The electrochemical device according to claim 12, wherein the substituent is crosslinked with a crosslinking agent. 18. The electrochemical device according to claim 12, wherein the fullerene molecule is crosslinked by the organic residue. 19. The fullerene molecule is a spherical carbon molecule C.
_m (m = 36, 60, 70, 76, 78, 80, 82,
Electrochemical device according to claim 11 or 12, consisting of a natural number capable of forming spherical molecules, such as 84. 20. The electrochemical device according to claim 11 or 12, wherein the proton conducting part made of the cation conductor is configured as a fuel cell arranged between a hydrogen electrode and an oxygen electrode.